Final answer:
An ancestor refers to a direct familial line, while ethnic groups are broader social and cultural communities with shared characteristics. Ancestors are specific individuals from the past, whereas ethnic groups are communities of people with shared cultural identities.
Step-by-step explanation:
An ancestor refers to a direct familial line, whereas ethnic groups are broader social and cultural communities with shared customs and traditions. An ancestor is a specific relative from the past, while ethnic groups are defined by shared cultural, linguistic, and historical characteristics that differentiate one community from another. An ancestor is an individual within one's lineage, while ethnic groups comprise communities of people with shared cultural identities, languages, and customs.